Key Input Control Circuit - Panasonic KX-T7453 Service Manual

AG3 50
---
A5V4 51
AP2HO 52
Analog
output
AP2HI 53
Analog
input
AP1HO 54
Analog
output
AP1HN 55
Analog
input
AP1HP 56
Analog
input
VREFM 57
---
AG4 58
APMO 59
Analog
input
APMN 60
Analog
input
6. BLOCK DIAGRAM
7. CIRCUIT OPERATIONS

7.1. KEY INPUT CONTROL CIRCUIT

1) Circuit Operation
Sequential input information (negativa logic) from the DSHS proprietary telephone is executed by
dynamic scanning.
The ports RR70 to RR73, RR80 to RR83 of IC6 are brought to low status consecutively.
If a key is pressed, the key-in information input is executed by ports R91 to R93, RB1, RB11, RB21,
RB0, RD1.
Power Ground terminal of analog circuit.
supply, etc. 5V power terminal of analog circuit.
Output terminal of microphone amplofier H2.
Connect the capacitor of 0.1
Inverting input terminal of microphone amplofier H2.
Analog
Connect the capacitor of 0.1
Output terminal of microphone amplofier H1.
Connect the capacitor of 0.1
Inverting input terminal of microphone amplofier H1.
Connect to the handset.
Analog
Non-inverting input terminal of microphone amplofier H1.
Power Reference voltage terminal of microphone amplifier.
supply, etc.
Connect the capacitor of 40
56 (MICG).
Ground terminal of analog circuit.
Output terminal of microphone amplifier.
Analog
Connect the capacitor of 0.1
Non-inverting input terminal of microphone amplofier M.
13
F to this terminal to cut the DC
F to this terminal to cut the DC
F to this terminal to cut the DC
F between this terminal and pi
F to this terminal to cut the DC